1. Field of the Disclosure
The present disclosure relates generally to performing a drilling and/or milling operation in a wellbore using a drill or mill operated by a hydraulically-operated motor.
2. Description of the Related Art
Many operations in wellbores for recovery of hydrocarbons (oil and gas) include milling a portion of a casing in the wellbore or forming a lateral wellbore from a main cased or open wellbore. Windows are milled or cut the side wells are formed from specified locations in the main wellbore. To perform such a milling or cutting operation during a single trip, a string containing a downhole tool (also referred to as the bottomhole assembly “BHA”) at a bottom end of a tubing, such as drill pipe or a coiled tubing, is conveyed in the wellbore that includes a cutting tool, such as a mill or drill, connected to a bottom end of a rotor of a fluid-operated motor, such as a progressive cavity motor, a whipstock connected to the mill or a body of the tool proximate the mill and an anchor below the whipstock. The whipstock is first oriented in the wellbore. The rotor of the motor is typically mechanically locked to prevent it from rotating the cutting tool and thus the whipstock. Once the whipstock has been oriented, the anchor attached below the whipstock is hydraulically set by flowing fluid through the locked motor and without breaking the mechanism locking the rotor in its locked position. After the anchor and whipstock have been set, the cutting device is mechanically disengaged from the whipstock, such as pulling or jarring the string or by hydraulically breaking the connection by supplying fluid to the motor above a threshold pressure. The cutting device is then lowered along the sliding side of the whipstock to perform the milling operation.
The disclosure herein provides downhole apparatus and methods that include a hydraulically-operated motor that is prevented from rotation while allowing a fluid to flow through a fluid passage in rotor to hydraulically set the anchor then blocking the fluid through the rotor and flowing the fluid to the motor to operate the motor to perform a milling/cutting operation by operating the motor.